Mechanochromism of dynamic disulfide bonds as a chromophoric indicator of adhesion strength for epoxy adhesive

Abstract

We demonstrated that the introduction of disulfide bonds into epoxy adhesive could be used as a facile chromophoric indicator to predict the adhesive strength. Once the disulfide bond was cleaved, the color of the epoxy adhesive would be changed from yellow to green due to the generation of thiyl radicals. The lifetime of this green coloration, so-called mechanochromism, was dependent on the crosslink density of the epoxy adhesive, namely, the adhesive strength.